Facile route to synthesize porous hierarchical Co3O4/CuO nanosheets with high porosity and excellent NOx sensing properties at room temperature

To fabricate sensors that are capable of ultrasensitive detection of NOx as well as optimize their synthetic route, highly porous and hierarchically structured Co3O4/CuO nanosheets were synthesized by a facile hydrothermal-calcination route. The CC2-1 sample synthesized with the 2:1 molar ratio of Co(NO3)(2).6H(2)O and CuCl2.2H(2)O has the most abundant porosity. Structural measurements found that the size of pore is 3.37 nm, the specific surface area is 24.04 m(2)g(-1), and the average slice thickness is about 5 nm. This optimum sample presented excellent NOx sensing performance at room temperature (RT = 21 degrees C), which has not only the highest response (14.16-1000 ppm), the shortest response time (2 s to 1000 ppm), and the minimum detection limit (0.01 ppm), but also good reversibility and selectivity. The superior property arises from the appropriate CuO ratio and the addition of pore-forming agent NaHCO3, and all together resulted in the unique hierarchical heterojunction structure, endowed with abundant porosity and a large number of defects, which eventually engender the remarkable chemisorbed ability to oxygen species. (C) 2018 Elsevier B.V. All rights reserved.